The present invention relates to glow elements for a vehicle cigar or cigarette lighters and, more particularly, to a glow element employing a semiconductor material.
In a vehicle cigar or cigarette lighter, glow elements are used which are supplied with current from the vehicle battery. Such elements consist of a metal pan in which a spirally wound heating conductor band is arranged. One extreme end of the heating conductor is welded, clamped or riveted on the pan. In the center of the pan, the other end is electrically connected to a pin or threaded bolt. This pin or threaded bolt is secured in the center of the pan.
The glow element are preferably made of a material with a rectangular cross section and are wound as a spiral. There are also arrangements where a coil of round heating conductor material is arranged spirally in the pan. These glow elements have the inherent deficiency that individual turns of the spiral can spring forward from the winding plane by jarring blows to the heating conductor when the cigarette lighter is disconnected. This can cause short circuits which, in turn, can destroy the heating conductor winding.
This deficiency must be eliminated by various measures, such as by profiling the heating conductor for mechanical hooking of the turns, or by providing a damping disk on the plug of the lighter in order to make the jarring blow harmless. The same function can be served by having heat resistant glazes or ceramic pastes which are embedded in the heating conductors.
In order to prevent interturn short circuits of the individual turns of the spiral, mica insulators were used in the past. At present, an electrically insulating oxide film is applied by special oxidation methods to the surface of the heating conductors. Such glow elements have the further disadvantage, however, that an inwardly bent deformed bimetal spring of the plugbox can be hooked with the top end between the heating conductor windings or between the heating conductor winding and the edge of the can, thus causing overheating of the lighter. Also, when wound heating conductors are used, a disadvantage is the unequal temperature distribution, with particularly low temperatures in the center of the glow spiral.